Artificial zenith.



E. H. LINDMAN. ARTIFICIAL ZENITH. APPuoATIoN FILED Nov. ze. 1911.

Patented Mar. 17, 1914.

ERIK H. LINDMAN, OF SEATTLE, WASHINGTON.

ARTIFICIAL ZENITH.

Zeniths Connected to SeXtants for Astronomical Observation, of which thefollowing is a specification.

My invention has for its primary object the provision of aconstructionfor determining the angle at the eye between an object and the Zenith,the invention being particularly useful for taking astronomicalobservations on water when the horizon is obscured or invisible,although it can obviously be employed in like capacity on land or in theair.

Briefly described, my invention comprises a Zenith indicator, with whichis associated means for directing a reiection from the same intocoincidence with the line of vision through a suitable sighting means.

I have shown my invention applied to a seXtant of well knownconstruction. It can however, as an attachment, be provided on anysuitable nautical or other instrument intended for astronomicalobservations.

I do not limit my invention for use as an attachment, for, ashereinbefore premised, my invention resides broadly in the provision ofa structure adapted or designed for determining ones position bymeasuring what I term the"zenith distance instead of the altitude.

Referring to the accompanying drawing, wherein like niunerals ofreference indicate like parts throughout: Figure 1 is a side elevationwith parts broken away, of my attachment removed. Fig. 2 is afragmentary vertical sectionof a seXtant equipped with my invention.Fig. 3 is a front elevation thereof, parts being broken away, and Fig.4L is a fragmentary perspective of the hood.

Referring to the drawing by characters of reference, 1 designates anarticial zenith indicator, having an indicator element shiftable throughthe influence of gravity. Indicator 1 conveniently comprises atransparent tube or chamber l containing preferably a dark or opaquefluid, and the movable indicator element in this construction consistsof a bubble A, as clearly shown, this permitting of the passage of lightthrough the indicator to a suitable mirror or refiector 2.

Specification of Letters Patent.

Application filed November 28, 1911.

Patented Mar. 17,1914..

Serial No. 662,847.

Reflector 2 is shown as consisting of the usual index glass of theseXtant, being fixed to radius 4, which latter has a hub part or boss aVprovided with a stub shaft 5 journaled in the plane or body l1 of theinstrument.

Reference numeral 6 indicates the vernier and 7 the usual graduated arccooperating therewith.

Tube or chamber 1 which is comparatively wide and flat is curvedconcentrically to shaft 5 and conveniently connected with a tube section1 of metal or other suitable material, the latter communicating with theopposite end portions of chamber 1 and thereby providing a continuouspassage for the fluid of the indicator, which continuous or circularpassage is not however absolutely essential.

Tube or chamber l is provided with a side rib 1a which is made fast, asby cement, in a groove of a wide bearing member or plate S to which isfixed a curved ring-like band 9 which latter, during the positioning ofmy device on a seXtant, is slipped over the hub part or boss 4L untilthe inner end portion of member or plate 8 bears against the end face ofsaid boss, see Fig. 3. A screw, as 10, is preferably employed to preventturning or accidental displacement of the attachment on the instrument.

Tube section 1 which is fixed to radial webs or arms 9', is providedwith a suitable filling aperture normally closed by a plug 12.

Reference numeral 13 indicates my object glass, this as shown,consisting of the usual horizon glass, and 14 indicates the eye piece ortelescope, this in conjunction with glass 18, constituting the means forsighting an object.

Reference numeral 20 indicates a hood adapted to be placed over chamber1, when an artificial light or illuminating means is required to obtaina reection of bubble A, the same resting on the end portions of saidchamber and having vertical side walls 20 20 which snugly fit the sidesthereof. Wall 20 forms an extension of a bottom wall 20, which latter isformed with an opening 20" through which a suitable illuminating means(not shown) is inserted during the taking of an observation.

In the use of my invention, for example, on a dark night, at sea, planeor body l1 is held in Vertical position. Then a known star or planet issighted through telescope 14 and the unsilvered halfl of glass 13.Following this, radius 4 is adjusted until the reflection of the bubbleof indicator 1 is received on the silvered half of glass 13 in line withthe object. Referring noW to arc 7 and Vernier 6 We read in degrees theindicate-d spacing of the object from the zenith, and by subtractingsuch reading from 90O We find the altitude.

Having thus described my invention What I claim as new, and desire tosecure by Letters Patent of the United States, is

l. A device of the character described comprising a body, a zenithindicator supported on said body for rot-ary movement, said indicatorcomprising a chamber partly filled with a fluid to thereby provide abubble, a reflector supported for movement in common with said indicatorand arranged to receive a reflection of the bubble thereof,

and means for sighting an object and simultaneously observing thereflection from said reflector.

- 2. A device of the character described comprising a body, a zenithindicator supported o-n said body for rotary movement, said indicatorcomprising a chamber partly filled with a fluid to thereby provide abubble, a reflector supported for movement in common with said indicatorand arranged to receive a reflection of the bubble thereof',..an

. object glass on said body having mirror and transparent sections, themirror section being arranged to receive a reflection from saidreflector, and an eye piece on said body for sighting an object throughthe transparent section of said glass.

3. A device of the character described comprising a body, a zenithindicator supported on said body for rotary movement,

said indicator comprising a transparent chamber curved concentrically toits center of movement and partly filled'vvith a colored fluid, areflector for reflecting the bubble of said indicator supported formovement in common with the latter, and means for simultaneouslysighting an object and the reiiectionV from said refiector.

4. In combination with a seXtant or like instrument, a zenith indicatorsupported for movement With the index glass thereof' to cast areflection thereon.

5. In combination With a sextantor like instrument, a zenith indicatorsupported for movement with the index glass thereof to cast a reflectionthereon, said indicator comprising a transparent chamber partly filledwith a fluid. Y

6. In combination with a seXtant or like instrument, a zenith indicatorsupported for movement with the index glass thereof to cast a reflectionthereon, said indicator com'- prising a transparent chamber partlyfilled with a fluid and curved concentrically to the center of theradius of' such instrument.

7. A device of the character described comprising a body, a zenithindicator supported on said body, said indicator comprising a chamberpartly filled With fluid, .a reflector pivotally supported on said bodyand arranged to receive a reflection from said indicator, an objectglass comprising adjacent sections one of which consists of'a reflectorarranged to receive the indicator reflection from said first namedrefiector, and means for sighting an object through said object glass.

ERIK II. LINDMAN. Witnesses:

P. Op HOLLAND, C. M. MILLER.

Copies of this patent may be obtained for ive cents each, by addressingthe Commissioner of Patents,

' Washington, D. C."

